especially with kids, i think the photo would have benefitted from seeing them front on. also, the location (walking in the street?!?!) doesn't add much to the image.
Multiple exposure? Cloning? :) Validate this! just kidding. I always find matching outfits hilarious. How can people tell them apart? Good photo. Wish you could see some faces and expressions but in this case not seeing them ads more to the power of the similarities.